Corals- mode of life

Looking at corals today, we find some species have a type of algae living inside them. these algae are called zooxanthellae. there is a symbiotic relationship between the algae and the coral. 

The soft tissue is not preserved, but we assume that fossil corals had samilar soft tissue to modern-day corals

conditions needed for good coral growth 

• need to be shallower than 30m - as need light
• clear waters so the algae can phtosynthesise
• high energy condiditions as need need well oxygenated waters
• temperatures beetween 23*C and 27*C
• found beetween 30* north and 30* south of the equator 

 types of modern reefs

• Fringing reef- must meet the land and some parts above sea level at low tide
• Barrier reef- further out to sea , with a lagoon seperating the land from the sea
• atolls or coral islands- ring shaped found far offshor. formed due to hot spot activity as the volcanoes create an area of shallow sea.